What is Radiation? Introduction Different Types of (dose) of radiation. A millirem is one Radiation one-thousandth of a rem. Radiation is energy in the form of waves or particles. Although Alpha particles travel only a few inches The average individual receives radiation is around us every day, in the air and lose energy almost as approximately 300 millirem of radiation you cannot see, hear, or smell it. soon as they encounter an obstacle such per year from natural background Radiation is detected by measuring as a sheet of paper or the outer layer sources. The legal radiation exposure limit for an 18-year old male, whose the activity of the energy released of a person’s skin. Alpha particles are profession allows or permits exposure, is as it decays. It comes from natural hazardous only when they are inhaled or 5,000 millirem per year; and 500 millirem and man-made sources as unstable ingested. for a woman during pregnancy. atoms decay to form more stable Beta particles can travel in the air for a atoms. few feet and can be stopped by a sheet of aluminum foil or glass. Beta particles Sources of Radiation can damage skin and eyes, but are most hazardous when swallowed or ingested. Radiation may be found everywhere, be it naturally occurring or from man-made Gamma rays are waves of pure energy sources. Natural sources of radiation and are similar to x-rays. They travel at include: the speed of light through air or open spaces. Concrete, lead, or steel must be • The human body. About 31 millirem used to block gamma rays. Gamma rays of the average person’s total are an external hazard. exposure emanates from within the body itself. Potassium-40 and other Neutrons are small particles that have radioactive isotopes found in the no electrical charge. They are released air, water and soil are incorporated during nuclear fission and can travel long into the food we eat, then into body distances in the air. Water or concrete tissue. are the best shielding against neutrons. Like gamma rays, neutrons can present • Terrestrial sources. Radon is the an external hazard. largest source of radiation exposure (~230 millirem/per year) in the United States. In addition, rocks, soil and Measurements of Radiation building materials derived from the earth’s crust, like granite, account for Radiation is measured in different ways: an additional 19 millirem per year.

• Rad (radiation absorbed dose) is the • Cosmic rays. The average person amount of energy actually absorbed receives about 30 millirem per year by human tissue. of their total exposure from cosmic • Roentgen describes the amount radiation from outer space. Cosmic of radiation energy, in the form of radiation increases with altitude, gamma or x-rays, in the air. roughly doubling every 6,000 feet.

• Rem (Roentgen equivalent man) measures the biological damage Medical Cosmic Man-made radiation 298 mrem 30 mrem sources include:

• Medical procedures such as x-rays, nuclear medicine,

and CAT scans Terrestrial Consumer Products (from Earth) expose the average 12 mrem American to another 19 mrem 29 millirem.

• Consumer products. The average American receives Radon Human Body 230 mrem about 12 millirem of 31 mrem their total exposure to radiation from consumer products. Exposure comes from smoke such effects increases with dose, but detectors, building materials, and the severity does not. Cancer is the television sets. Lawn fertilizer only observed clinical manifestation of can also expose an individual to radiation-induced stochastic effects. radiation. Fertilizer contains trace There is a substantial delay between the amounts of potassium-40, a naturally time of exposure and the appearance of radioactive material. the cancer. Stochastic radiation can also damage the germ cells (ova and sperm) Less than one percent of total exposure- to produce hereditary effects. comes from a variety of other sources, including fallout from past testing of nuclear weapons, and from the generation of electricity in nuclear, coal- Protection fired, and geothermal power plants. To protect your self from radiation, there are three basic concepts to keep in mind: time, distance, and shielding. The Radiation’s Effects on amount of radiation exposure is directly Humans related to the amount of time spent near the source of radiation, the distance The nature and extent of damage caused from the radiation, and the shielding by ionizing radiation depends on the between you and the source of radiation. amount of exposure, the frequency of The less time spent near the source, at exposure, and the penetrating power of the greatest distance, with the greatest For more information, contact: the radiation to which an individual is shield will result in the least exposure. U.S. Department of Energy exposed. There are two main types of National Nuclear Security Administration Nevada Field Office radiation effects on humans: Office of Public Affairs Deterministic radiation occurs at P.O. Box 98518 the cellular level. Effects are usually Las Vegas, NV 89193-8518 manifested soon after exposure. The severity of the effect increases with dose. Phone: 702.295.3521 Examples include radiation skin burning, Fax: 702.295.0154 blood count effects, and cataracts. Email: [email protected] In contrast, stochastic radiation effects www.nnss.gov are caused by more subtle radiation- induced cellular changes (usually DNA mutations). The probability of DOE/NV - -1043 April 2017